Flow-sensing system and valve

ABSTRACT

A digital hydraulic system converts binary digital input information into displacement of a digital drive. An air reader is used to operate binary latch valves through an air hydraulic interface. A flow-sensing system and a hydraulic logic unit cooperate to provide high-speed exchange between the piston adders of the digital drive prior to displacement of the load. A hydraulic cylinder sweeps the load about a vertical axis. A selfcooling, air-driven hydraulic pump with an accumulator provides relatively constant pressure. A damper secured to the piston adders has an additional drive for providing precise location at the end of damping. An incremental paper tape feed with a four motion rack with toggle action operates the air reader.

Unite Hebert tates tent Feb.15,1972

[54] FLOW-SENSING SYSTEM AND VALVE [22] Filed: May 14,1969

[21] Appl.No.: 824,425

Primary ExaminerEdgar W. Geoghegan Assistant Examiner-Allen M. Ostrager Attorney-Hamlin and Jancin and Graham S. Jones, 11

[. ABSTRACT A digital hydraulic system converts binary digital input information into displacement of a digital drive. An air reader is used to operate binary latch valves through an air hydraulic interface. A flow-sensing system and a hydraulic logic unit cooperate to provide high-speed exchange between the piston adders of the digital drive prior to displacement of the load. A hydraulic cylinder sweeps the load about a vertical axis. A self-cooling, air-driven hydraulic pump with an accumulator provides relatively constant pressure. A damper secured to the piston adders has an additional drive for providing precise location at the end of damping. An incremental paper tape feed with a four motion rack with toggle action operates the air reader.

10 Claims, 18 Drawing Figures TO DIAPHRAGMS PATENTEB EB 1 3.841.877

SHEET UlUF 14 Tl1\ PE 11 4 swncnmc 15 1o 141,142 HYDRAULIC 1 VELOCITY BINARY AIR Am CONTROL LATCH HYDRAULIC VALVE VALVES INTERFACE READER T RESET PEA o R TE 542\ 141.142 1 \88 PROBE \TOCGLE 115 DR VE 1111:11 76 116 111121 1 1 EXCHANGE PSTON & MOVE HYDRAULIC DAMPER FLOW POWER ADDERS S SENSING SUPPLY 156 v SYSTEM 7 15 152 386 1 75 7 BYPA g; c; "'BLEED 116 CONTROL s4 HYDRAULiC LOGIC START ON-OFF fi /94 2o 53 Y DECODER 50 WITH ALIGNERS TREE 2s 52/ CLAMP RACK 2oo 198 MED SWEEP 196 [34 3 sENsE \zosi SWEEP CYLINDER SWEEP 197 209 R SENSE r T INVENTOR 204 1101111111 0. mm

PATEWE FEB w I972 SHEET OBBF i4 PATENTEB EB 7 I972 SHEET 0% HF 14 SHEET user 14 PAIENFEFEB 15 I972 PAIENTEUFEB 15 m2 SHEET OBUF 14 M2: MEQE PATENTEDFEB 15 1912 SHEET OSUF 14 ME: m2:

IN INCHES DISPLACEMENT PTEDFEB I5 I97? 3, 41 77 sum 12 OF 14 FIG. FIG. I 3A 5A 3B ISOLATION VALVE O- PURGE CONTROL VALVE O- LOAD 1 VELOCITY CONTROL VALVE O REAOER RACK PISTON O READER TOGGLE VALVE O- ALIGNER PISTON O ALIGNER VALVE O ALIGNER DELAY PISTON O ALIGNER LATCH VALVE O DAMPER PISTON DAMPER DELAY PISTON- DAMPER VALVE EXCHANGE VALVE MOVE VALVE MOVE SENSE VALVE EXCHANGE SENSE VALVE BYPASS POPPET I" CYLINDER NO.I LATCH VALVE 2" CYLINDER N02 LATCH VALVE N02 PILOT VALVE MOVE DELAY PISTON FLOW VALVE FLOW VALVE PISTON START VALVE PROBE VALVE PROBE DELAY PISTON PROBE PHASE PISTON 2O 4O 6O 80 I00 I20 I40 160 I80 200 TIME IN MILLISECONDS PAI'ETED FEB 15 I972 SHEET 130E 14 -I2OMS LllIllllllIllllLllllllllllll 220 240 260 280 500 520 340 360..

TIME IN MILLISECONDS ISOLATION VALVE PURCE CONTROL VALVE LOAD VELOCITY CONTROL VALVE READER RACK PISTON READER TOCCLE VALVE ALICNER PISTON ALICNER VALVE ALICNER DELAY PISTON ALICNER LATCH VALVE DAMPER PISTON DAMPER DELAY PISTON DAMPER VALVE EXCHANGE VALVE MOVE VALVE MOVE SENSE VALVE EXCHANGE SENSE VALVE BYPASS POPPET 1" CYLINDER NO. I LATCH VALVE 2" CYLINDER NO.2 LATCH VALVE N02 PILOT VALVE MOVE DELAY PISTON FLOW VALVE FLOW VALVE PISTON START VALVE PROBE VALVE PROBE DELAY PISTON PROBE PHASE PISTON FLOW-SENSING SYSTEM AND VALVE CROSS-REFERENCE TO RELATED APPLICATION This application is related to U.S. Pat. application, Ser. No. 824,424 entitled Integrated Adder Drive Assembly Including Damper, Hydraulic Power Supply, And Paper Tape Feed" filed herewith.

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to fluid sensing and control devices. More particularly, this invention relates to fluid flow-sensitive devices for varying the orifices in a hydraulic displacement system. More particularly, this invention relates to means for providing a variable flow rate in conjunction with flow sensing and control means.

In another aspect, this invention relates to providing a variable rate of displacement of an arithmetic drive between exchange between displacement numbers when idling and subsequent displacement of the load.

2. Description of the Prior Art Flow valves in the prior art have been used for controlling the operation of a system in response to decline of flow below a predetermined level, as in U.S. Pat. No. 3,575,301 application Ser. No. 694,941 of H. A. Panissidi entitled Manipulator." In that case, the displacement of the load occurred at a fixed velocity.

Variation in the size of an orifice has been employed in prior hydraulic control systems for the purpose of varying the velocity of operation of a hydraulic motor. Such controls may provide more than two velocities of operation ofa fluid-extensible device.

SUMMARY OF THE INVENTION in accordance with this invention, means are provided for operating an arithmetic drive at a relatively high velocity provided that its output shaft is held in a fixed position during the initial period of each displacement step, during which time the various elements of the arithmetic drive are interchanging or exchanging position.

Another aspect of this invention comprises the provision of a pair of flow-sensing switches, one of which is controlled by means of a bypass poppet which is externally operated. Accordingly, the pair of flow sensing switching devices may be employed to provide two different modes of operation of a control system.

Further in accordance with this invention an automatic variable orifice system is provided whereby a piston adder drive may be operated at a high velocity during a period during which the load is not being displaced and the adder pistons are simply exchanging position with each other. Subsequently, upon decline of flow velocity below a predetermined level, the control system will cause the piston adder drive output clamp to be released, and the fluid moving at a lower flow velocity is supplied through a reduced orifice to displace the load at a reduced velocity.

An object of this invention is to provide displacement of a load by means of an arithmetic drive at an optimum velocity.

Another object of this invention is to provide high velocity displacement of a load with minimum time delay between displacement cycles when employing a highly accurate arithmetic drive.

A further object of this invention is to provide high-velocity displacement of a piston adder drive assembly during an initial exchange period of operation.

Still another object of this invention is to provide displacement of a load by means of a sequential, arithmetic drive with minimal delay between motions of the drive.

The foregoing and other objects, features and advantages of the invention will be apparent from the following more particular description of the preferred embodiment of the invention as illustrated in the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. I shows a schematic block diagram of the overall system employed in accordance with this invention.

FIG. 2 shows the relationship between the various sections of the large diagram of FIGS. 2A-2L.

FIGS. 2A2L show the overall connections between the various subsystems of the integrated adder drive assembly employed in accordance with this invention, and in FIGS. 2K and 2L additional details of the system are shown.

FIG. 3 shows the relationship between FIGS. 3A-3B.

FIGS. 3A and 3B show the displacement characteristics of valves and mechanism in the hydraulic system shown in FIGS. 1 and 2A--2K in accordance with this invention as a function of time.

FIG. 4 shows the sweep and arm clamping mechanisms for the base ofa manipulators arm.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Control System Referring to FIG. I, the present system includes an air reader 10 for reading a perforated tape 11 which provides output pulses to a hydraulic control system by means of an air line 12 and an air hydraulic interface 13 which converts pneumatic pulses to hydraulic values. The air hydraulic interface transfers pulse inputs to hydraulic binary latch valves 14 which "remember or retain a or a l condition, depending upon the sense or polarity of the input transmitted from reader through the interface 13.

The outputs of the latch valves are in general connected via lines 141, 142 to extend or retract a corresponding one of several piston adders 15 which comprise a series of interconnected pistons and cylinders employed to provide binary displacement of a load-bearing shaft 156 by unit distances, in binary progression from one thirty-second inch to almost 32 inches in binary steps up to 16 inches.

For the 1-, 2-, 4-, 8- and l6-inch-long piston adders, a set of variable orifices in a velocity control valve 17 are provided between lines 141, 142 and 342 for the purpose of controlling the rate of displacement of the pistons with larger displacements.

In order that the piston adders l5 and the output shaft 156 connected to one end thereof may be accurately located rapidly, a damper 18 is provided which permits the piston adders 15 to be cocked during an exchange interval.

The exchange interval is a time during which the output shaft 156 is firmly retained in position by braking or arresting means shown in part herein shown in full in above U.S. Pat. No. 3,575,301 and the piston adders 15 are reset and extended to the extent that certain pistons are retracted and certain other pistons are extended. During the exchange period the velocity control valve 17 will be held wide open to permit exchange at maximum permissable velocity, since the piston adders 15 will not be under load. The flow system 23 includes restrictive passageways 42, 44, 49 and orifices 50 and restrictive bypass valve 41 for varying the resistance of flow of fluid through the hydraulic circuit to the piston adder drive 15. A hydraulic logic unit 20 responds to an output of system 23 on line 25 to close valve 40 to increase the resistance to flow through system 23 to drive 15. Hydraulic logic unit 20 also concurrently releases the braking means controlled by aligner lines 174, 175, 180 and 181. The braking or arresting means are released through line 94, and decoder which selectively releases aligners 31, which with cable 469 serve to brake the output shaft 156 by preventing motion of the drive cable 469 shown in FIG. 4 and shown in detail in above U.S. Pat. No. 3,575,301, which thereby prevents motion of member 367 and shaft 156 secured thereto. Exchange piston and move piston 36 biased by springs 43 respond to decline of flow velocity below a predetermined level to cause lines 24 and 25 to sense such decline by disconnecting those lines from a zero pressure return line 46. The move piston operates with line 24 for sensing the termination of a step of operation of the arithmetic piston adder drive 15.

. Referring again to the damper 18, when the load has been fully positioned where desired, the damper 18 provides hydraulic damping with minimum overshoot and is actuated via line 75 by hydraulic logic unit 20 to provide mechanical positioning ultimately to a precise home position. Cooking minimizes overshoot and optimizes use of time for the steps of exchanging piston locations and driving the load.

In order to provide regulated hydraulic pressure to the system a hydraulic power supply 22 is provided. It supplies pressure for latching and to the central lands 16 of spool valves in the hydraulic logic unit via line 116 and the flow sensing system 23, via line 47, which controls two bleed lines 24 and to the hydraulic logic unit 20 as a function of the velocity of flow through line 47, the flow-sensing system 23 and line 52 to the latch valves 14 which connect to the piston adders 15. When the flow or displacement of piston adders declines below a minimum value the bleed lines 24 and 25 are blocked by flow-sensing system 23. A bypass control line 38 from the hydraulic logic unit 20 controls a port 40, 41 inside the flow-sensing system 23 to control one of the flowsensing units therein.

The hydraulic logic unit 20 can be started and stopped. Since the logic unit 20 controls the toggle line 76 which powers the feed advance of the tape reader 10, when switch 54 is operated, air is blocked from operating the logic unit 20 and at the end of a displacement cycle operation of the system stops.

As the drive is adapted to displace a plurality of members, a decoder is connected to the logic unit 20 via line 94, and to certain ones of the latch valves 14, to operate aligners 31 to hold the various members to be displaced by the output shaft, through a linkage, not shown, which is similar to that shown in copending U.S. Pat. No. 3,575,301 application Ser. No, 694,941. Clamp rack 32 is engaged when it is desired to drive the Z arm of the output, for example, a manipulator, as shown in FIG. 4.

A set of sweep sense units 33 and a sweep cylinder 34 are employed to sweep a load on support 190 about an axis upon an input via line 198 or 200 from one of the latch valves 14. The sweep sense unit 33 is connected to bleed line 25.

Referring to FIGS. 2A-2J, the overall system is shown in greater detail than in FIG. 1 and the connections between the various systems are shown.

EXCHANGE AND VARIABLE VELOCITY CONTROL The exchange and move flow sensing system 23 includes a cylindrical exchange sense piston 35, a cylindrical move sense piston 36 and a bypass poppet 37. The bypass poppet 37 is controlled by pressure in a line 38 connected to the lower output of flow spool valve 39 in FIG. 2B. When pressure in line 38 is above return pressure, it drives piston 37 to the right to open valve 40 by moving it away from surface 41. When there is no pressure in line 38 which results when line 38 is connected to a zero pressure return line, as via groove 95, when valve 39 is down, then piston 37 moves left closing valve 40. When the bypass poppet 37 is to the left, its valve 40 will seat on surface 41 to close off the inlet 42 to the exchange sense piston 35. It should be noted that the exchange sense piston 35 and the move sense piston 36 are each spring biased by springs 43, coaxial therewith in the larger coaxial bore 44 in the pistons 35 and 36. The pistons 35 and 36 have annular grooves 45 to connect the bleed lines 24 and 25 to the return 46 to the low pressure side of the hydraulic pressure supply 22. When piston 35 blocks bleed line 25 from return 46, as the result of a low flow rate through orifice 50 of piston 35, then after a time delay hydraulic logic 20 removes pressure from line 38, by driving flow spool valve 39 down which pulls piston 37 left to close valve 40 on surface 41. Valve 39 connects line 38 to zero pressure, i.e., return pressure via groove 95.

When the exchange sense piston 35 falls back under spring bias, to block bleed line 25 and signals the hydraulic logic 12 through bleed line 25, it also causes aligner valve 92 to rise to remove pressure from line 94 concurrently with closing of valve 40. Then the braking or arresting action of one of the aligners 31 can be withdrawn through drainage of oil through line 94 to return 12. Thus, at the end of exchange, the selected one of the aligners 31 will permit the output shaft 156 to move the aggregate distance that the piston adders 15 are caused to move by their binary latch valves 14, When piston 35 is actuated at the beginning of the next exchange cycle, piston 35 will open bleed line 25 to signal hydraulic logic 12 which will restore pressure on line 94 to lock all aligners 31 and to brake shaft 156. Pressure from the hydraulic pressure supply 22 is supplied by line 47 to the inlet 48 on the upstream end of the valve 40 of the bypass poppet 37 which may or may not be open, as described above, and to the inlet 49 to the move sense piston 36. Hydraulic line 47 is connected to hydraulic line 52 through system 23 via inlet 48, which connects via inlet 49, orifice 50, coaxial bore 44, and line 51 connected to line 52, and in parallel, when valve 40 is open, through inlet 48, through port 41, past valve 40, through inlet 42, through orifice 50, through coaxial bore 44, and through line 51 to line 52 also. Each of the exchange sense piston 35 and the move sense piston 36 is provided with a smaller axial bore 50 to the upstream end thereof confronting the corresponding inlet 42 or 49 thereof. The orifices 50 are selected so that when the pressure differential across the orifice 50 is above a predetermined level, then the pistons will be driven upwardly against the pressure of the springs 43 to align the grooves 45 with the bleed lines 24 and 25, thereby connecting the bleed lines to return 46. The bypass poppet 37 provides a means for selectively actuating the exchange sense piston 35. in this way, the flow sensing system may be operated in two modes depending on whether the piston adders 15 are being driven in the move or exchange mode of operation. A further feature of this system is that since each of the orifices 50 is substantially of the same order of magnitude in diameter and length, the resistance to fluid flow provided by each thereof is substantially of the same order of magnitude. When both are connected in parallel, the resistance to flow is nearly halved, or conversely, flow doubles, approximately. As will be noted, the outlets 51 of the two sense pistons are connected to line 52. Since the two sense pistons are in parallel, and therefore the orifices 50 are in parallel, if the bypass valve 40 is open, the quantity of flow through each of the two orifices 50 will be substantially equal and accordingly the rate of flow into the line 52, if sufficiently large and unrestricted will in general be approximately doubled. Accordingly, when the exchange sense piston 35 is permitted to operate by the bypass poppet 37, the quantity of fluid flowing from lines 51 through line 52 to the piston adder drive will be greater and the velocity of displacement in the exchange period will accordingly be far greater.

HYDRAULlC LOGIC UNIT The hydraulic logic unit comprises a plurality of spool valves, delay pistons in cylinders which comprise compliance or capacitive units which require a time delay for displacement from one end to the other end of the cylinder in which they are housed; orifices, check units described below in connection with FIG. 2L, interconnections and outlets which control other elements of the overall system. Certain of the spool valves are spring biased into one position as indicated by helical springs in longitudinal cross section. Certain other of the spool valves are latch valves which are held in position by hydrauliclatching means. Such a latching means comprises a passageway 600 tangential to one end of a land of a spool located so that it supplies fluid under pressure to the side of the land regardless of spool position, and contacts a small area on one side. The land thereby creates a laminar pressure gradient along that side which is coupled to the return lines through leakage. There is a ratio of pressure across the land of several times the pressure on the inlet side to the pressure on the low pressure side which pushes the land to one side and inhibits longitudinal sliding because of friction forces. Pressure can be relieved during movement of the spools to relieve friction forces.

When the start diaphragm 56 is operated by the pressure at inlet 53 (assuming pneumatic toggle 54 is on) from the reader start apertures 28 in the tape via line 29, or otherwise provides input from a two way solenoid or valve 27, etc., then the start spool valve 55 is driven upwardly thereby connecting its lines 57 to the right and to the left to higher pressure from the central annular groove 16 as the central land or ring passes thereabove. Accordingly, pressure will be applied at the junction 58 between the orifice checks (described below in connection with FIG. 2L, 59 and 60 which connect to the probe spool valve 61, the probe delay piston 62, and the probe phase piston 63. On the left side, the line 57 is connected to the point 64 which supplies the lower end of flow spool valve 39; and by orifice check 65 point 64 is connected to line 66 and phase piston 67. It will be noted that line 66 is connected to bleed line 25 and both are connected to the upper end of the flow spool 39, valve which is spring biased downwardly. Accordingly, when the flow phase piston 67 has moved fully to the top of its cylinder at the end of 60 milliseconds, then as soon as the exchange sense valve causes the bleed line 25 to be disconnected from the return 46, the pressure on the line 25, and therefore on the upper end of the flow spool valve will be increased and the flow spool valve will be driven back to its position as shown in FIG. 28 by the force of the spring 87. Initially, then, as soon as the start valve is operated, the flow valve will be operated also and pressure will be placed upon line 38 from the central high-pressure source and line 38 will connect pressure to the bypass poppet 37, which will remain open until the flow valve is driven back to its home position. Since line 38 is connected to the lower end of delay piston 68 and to the lower end of move spool valve 69 which is biased upwardly, the move valve will be driven rather rapidly upwardly shortly after the flow valve is driven upwardly, by the spring 53. It should be noted that later, when flow is reversed, the delay piston 68 cooperates with the orifice check 70 to provide a long time delay before it is possible for the move valve 69 to be reset down against the force of its spring 53. When the move valve is driven upwardly, the line 71 from the upper end thereof has the pressure thereon released, thereby releasing pressure on the upper end of the exchange spool valve 72 which will have pressure on the lower end thereof from the line 38 which, after the delay valves have permitted the pressure to build, will then shift upwardly. The damp spool valve 73 has a spring bias at the lower end thereof, and will shift shortly after the exchange valves shifts, thus releasing the pressure from the upper end thereof. Line 75 is connected to the damper 18 including its pistons as shown in FIG. 1 and FIG. 21 secured to one end of the piston adders 15. At this point in each displacement cycle of the drive, pressure is released from the damper positioning pistons 80. Accordingly, the damper is released so that it can be cocked during the exchange mode of operation. After an interval of about milliseconds selected to allow pilot valves 85 to be positioned, according to the data in the tape, the probe delay piston 62 will have reached the opposite end of its cylinder. Accordingly, the pressure at the lower end of the probe spool valve 61 will have reached a high enough level to overcome the spring biasing force at its upper end and to drive the valve upwardly thereby providing pressure on probe line 81 from the central annular pressure source 82 as the central land passes thereacross and the lower land passes across the return 83. The probe line 81 is connected to each of the inlets 84 of the pilot valves 85 to provide pressure to their central annular cavities. The probe pressure is employed to adjust the hydraulic binary latch valves 14 in accordance with the binary values provided by the air reader 10. Thus, the binary drive will be reset in accordance with the most recent input data provided thereto in the tape under the air reader 10. It will be understood that another variety of input source could be connected through a suitable interface. About 40 milliseconds after start, the probe phase piston 63 will rise to the top of its somewhat longer cylinder and at that time will cause a pressure buildup at its lower end, which is connected to the upper end of the probe spool valve 61 which is spring biased downwardly. Since the pressures of the opposite ends of the probe spool valve 61 will be equal and opposite, accordingly, the probe spool valve will be driven downwardly by its spring 86. At this time pressure will be removed from the probe line 81. This will not mean the end of the exchange motion of the piston adders which will be under control of the hydraulic latch valves 14 which will remain as positioned during the probe portion of the control cycle of the hydraulic logic circuit 20. So long as the exchange continues, the exchange sense piston 35 will remain in its upper position against its spring as will the move sense piston. At a predetermined point, when the exchange velocity ends and the flow of hydraulic fluid due to elimination of pressure differential and the end of flow through the sense pistons 35 and 36, they will both move down to their spring biased lower positions. Accordingly, bleed line 24 will be closed momentarily and bleed line 25 will be closed for the remainder of each cycle of operation of the hydraulic logic unit 20. Line 25 will thereby cause buildup of pressure on the upper end of the flow valve 39 as mentioned above and the spring 87 at the top thereof will act to drive the flow valve 39 down. Pressure will build on the line 24 and line 89 from lines 16 and 688 through the flow valve 39. However, the delay piston 68 and the orifice in orifice check 70 will defer the buildup of the pressure in the lines 24 and the buildup of the inlet 89 to move valve 69, and actually the move valve 69 will not be operated at this time, because, a short time later, bleed line 24 will be reconnected by move sense piston 36 to the return 46 and will bleed pressure from inlet 89. Line 688 will apply pressure immediately to the central cylindrical cavity 188 of the exchange spool valve 72 held up by pressure in line 38 and thereby providing pressure on line 90 to the lower end of the aligner latch valve 74. The aligner latch valve 74 will be driven upwardly since the upper end thereof will have low pressure, as on line 75. The pressure had been released as described above. Accordingly, the aligner latch valve will release pressure on line 91 to permit the aligner spool valve 92 to be driven upwardly by a spring 93. This will apply pressure to line 189 resetting start spool valve 55 applying pressure from line 116 to reset line 88 to reset all of the pilot valves 85 and will release pressure from line 94 which is connected to the aligners 31 so that one of the members connected to the output of the load shaft can be driven at this point. Further, line 94 is also connected to the velocity control valve 17 in order to reduce the orifice into the piston adders during the period of driving of the load. As the load is now free to move, the piston adders can move and accordingly flow will resume in line 52 (as indicated above in connection with line 24) and for that reason the pressure drop across the move sense piston will resume and the move sense piston will be driven upwardly again thereby bleeding pressure from the bleed line 24. However, the bypass poppet 37 will have pressure released therefrom on line 38 since the flow valve 39 will, as described above, have been driven downwardly thereby connecting line 38 to the return 95. Pressure on line 76 from aligner latch valve 74 in FIG. 2A to the reader 10, FIG. 2D, will operate the reader feed mechanism. In addition, in the purge control in FIG. 2B, pressure in line 76, will operate a pair of pistons 96 from line 97 attached to the line 76 to drive the spool valves 98 and 99 to the left so that the pressure on line 100 will be connected down into the lines 101 which are connected to the purge inlets, to the diaphragms 102 in the air hydraulic interface 13. Air under 10 p.s.i.g. pressure will be driven through the purge inlets 101 across the surface of the diaphragms of the interfaces 102 and out through the reader lines 12 to purge or to drive oil out of the system and to clear and chad and other material from the lines 12, and 112. The remainder of the purge cycle is described below, after discussion of concurrent valve operations.

The pressure will remain on line 76 until such time as the motion of the piston adders ends and the move valve 69 is driven downwardly by final closure of the bleed line 24 by closure of the move sense piston 36, so that at that time, line 71 will drive the exchange valve 72 down removing pressure from line 911 and at the same time applying pressure to line 103 through the orifice or orifice check 104 and delay piston 105 after a time delay of 90 milliseconds, drive the damp valve 73 down against its spring and to apply pressure on line 75 therefrom to drive the aligner latch valve 74 down and remove pressure from line 76 and apply pressure to line 91 and through the orifice in the orifice check 106 and delay piston 107 cause a time delay to run to drive the aligner valve 92 down against its spring 93. The aligner delay piston 107 will require another 120 milliseconds to drive downwardly. Accordingly, final alignment will not occur for some time.

However, referring again to the purge unit, in FIG. 2B, when line 71 is pressurized, the piston 99 will be driven to the right and atmospheric pressure from line 199, to atmosphere, will be permitted to resume inside the purge and reader lines 101 and 12 so that the diaphragms 102 may be returned to atmospheric pressurev Then when pressure is removed from line 76 as a result of return of the aligner latch value to its lower position, the spring 108 of the spool valve 98 will act to drive that spool valve to the right and to shut off connections to the diaphragms. lt should be noted that the lO-p.s.i.g. air supply 109 is connected to line 110 which applies positive pressure to the air pressure head 111 for passage through the tape 11 into the inlets 12 to the diaphragms 102.

During the time that the purge spool valve 98 is to the left, the blocking of pressure by valve 98 from line 110 to the air reader 1 11 will prevent blowing air down into the diaphragms during the purge cycle when air is to be blown in the reverse direction AIR READER The perforated tape reader shown in FIG. 2D will operate in ordinary machine shop air typical of industrial locations, which is contaminated with dirt, oil and water. Therefore, cyclic purging of lines 12 is necessary because the reader sense hoses are extremely thin, usually 0.030 inches I.D. making them vulnerable to clogging,

in order to avoid costly memory devices and serial to parallel converters for some applications, the reader is designed to advance the tape up to two characters per step, allowing the system to accept two characters of data simultaneously. The hydraulically driven reader, as shown schematically, consists of an air reader head with 16 ports to accept two perforated characters of an eight-channel Mylar tape. The 16 ports of the air reader head are connected by sense hoses to the 16 diaphragm driven hydraulic pilot valves. The air reader head, supporting the tape, is pressurized with 10 p.s.i.g. air by a spring-loaded air manifold. A hole in the tape will allow its corresponding diaphragm actuated pilot valve to be pressurized with 10 p.s.i.g. from the air manifold.

The air reader 10 includes an air pressure head 111 which is spring biased downwardly by a spring 117. The tape which is used includes eight longitudinal columns and is read in groups of two rows of characters such, as shown in FIG. 2D, simultaneously. Accordingly, the feed must advance two rows of holes for each reading cycle. The top hole in the first row is the start control. The next two holes are M2 and M1 controls for FIG. 2E and the next holes ones are the fractions from onehalf inch down to one thirty-second inch. in the second column in the second hole, the sweep mode of operation of the manipulator which would be attached to the device is entered and in the third hole, the bit for the grip mode of operation ofa manipulator gripper would be entered. in the last five holes in the second column, the bits for the 16-, 8-, 4-, 2-, and l-inch piston adders would be entered. The head 111 is designed so as to provide air pressure above all 16 holes and underneath the holes would be aligned the various inlets 12 to the diagrams 102 shown in F168. 2E-2l-l. The feeding mechanism is comprised of a sprocket wheel 118 which operates in cooperation with perforations 119 in the tape 11. The sprocket wheel 118 is secured to shaft 120 and the shaft 120 is journaled for rotation in response to torque applied by gear 121 which is retained in position by detent pawl 122 which is spring-biased downwardly by spring 123. The pawl 122 carries a pin 124 at one end thereof which fits into the teeth of gear 121. The gear 121 is adapted to mesh with a rack 125 which can be raised into gear by a toggle lever 126 which is pivotally secured by pin 127 in which toggle lever carries rack 125 on pin 128. The rack 125 is reciprocably longitudinally slidable on drive wire 129 secured at its distal end to a piston 130 slideably carried in cylinder 131 for longitudinal reciprocation therein. The cylinder 131 contains a spring 132 at the distal end of the piston 130 for biasing the piston 130 leftwardly. At the opposite end of the cylinder is a release aperture 333 to permit motion to the right. The opposite end of the toggle lever 126 is secured to a drive wire 133 by means of pin 134 to bifurcated end 135 of drive wire 133. Drive wire 133 is secured at its distal end to a spool valve 136 carried in cylinder 137. The spool valve 136 is spring-biased leftwardly by spring 138. At the leftward end ofpiston 130 is an inlet 139 connected from the central portion of cylinder 137 adapted for communication with the two inlets 81 and 281 into the lower cylinder 137 from the central portion thereof. At the leftward extreme end of cylinder 137 is located an inlet from line 76 from the aligner latch valve lower outlet, which is provided for operating the readerv lf pressure were applied to line 76, it would function to pull the toggle lever 126 counterclockwise about pin 127 by means of flexing of drive wire 133. Lever 126 and pin 128 will drive the rack 125 up into engagement with the gear 121 preparatory to actual driving motion. When this occurs, i.e., valve 77 is to the right, the connection of line 139 to the cylinder 137 will be made to the line 116. This will drive the piston 130 to the right against the reaction of its spring 132 pulling wire 129 and the rack 125 to the right and turning the gear 121 counterclockwise about shaft 120 thereby advancing the tape 11 two character positions to the left as the sprocket 118 is turned on the shaft 120 counterclockwise. lt should be noted that while the probe pressure is employed for the purpose of driving the air reader, that such probing does not occur until after the pressure on the purge line 76 has been generated by means of driving the aligner latch valve 74 to its upper position after the exchange is terminated. The adjustment of the pilot valves during the probe cycle will have been completed well prior to that time; and with the application of pressure on line 76, and the displacement of the purge spool valve 98 to the left, the pressure applied on line 110 to the air pressure head 11] will have been blocked by the leftward land of the spool valve 98.

During the period the rack rotates the drive gear, there is a substantial separating force between the rack and gear due to the pressure angle of the gear teeth (20) which is supported by the toggle shaft.

With pressure removed from the left end of the toggle valve, its spring will drive it to the left rotating the toggle lever 126 to its initial position. The toggle valve will expose port 139 to its port 281, thereby removing pressure from the left-hand side of the drive piston allowing it and its rack to return to its initial position by the reaction of its spring.

It is during this tape advance cycle described above that the pilot valves 85 of the hydraulic system must be physically locked by pressure in line 88 from responding to the tape holes as they move under the air reader head 111, and at the same time, the sense hoses 12, diaphragrns 102 and air reader ports must be flushed out with a reverse air blast to purge the air-sense system of any contamination from the previous read cycle. Line 76 to the purge control 99 and isolating valves 98, respectively, causes both valves to move to the left, valve 98 moving against the reaction of its spring 108. The transfer of the multiple land isolating valve 98 will expose all of the purge hoses 101 to the port 100 of the transferred purge control valve 99 and, at the same time, shut off the air pressure to the air manifold 110 by the scissoring action of the extreme lefthand land of the isolating valve 98,

The port 101) of the purge control valve exposed to its 10 p.s.i.g. port 109 provides a reverse airflow through the 16 diaphragm chambers, sense hoses and the air reader head ports with the foreign matter, if any, being expelled between the air reader head and tape to the atmosphere. Following this purge cycle, the entire reading circuit and diaphragms must be depressurized before releasing the locked diaphragm actuated pilot valves. In order to accomplish the depressurization, the purge control valve must be returned to its initial position before the return of the isolating valve 98 sealing off all the purge hoses 101.

A time delay network consisting of an orifice in series with move delay piston 68 controls return of the purge control valve 99 to its initial position for exposing all the purge hoses to the atmosphere through port 281. Again at the end of the tape advance cycle the aligner latch valve 74 will be restored to its initial position with the removal of the hydraulic signal, exposing line 76 to the reservoir allowing the tape advance circuit and isolating valve to reset to their initial position.

The reset of the isolating valve will permit air pressure to the air manifold and, at the same time, seal the individual purge hoses to prevent crosstalk. With the release of the locking pressure from the pilot valves, it will allow the diaphragms to respond to a hole in the tape causing the transfer of the pilot valve against the reaction ofits spring.

An advantage of the above described pneumatic tape reader is that it has a minimal number of moving parts, is capable of reading two characters simultaneously, and in contrast with the type of reader which had been required in connection with this type of system before, eliminates the need for a character buffer storage unit.

Use of pressure instead of vacuum sensing of the tape holes minimizes the problem of contamination and costly filtration.

AIR HYDRAULIC INTERFACE From the lines 12 of the air reader 10, connection is made, as described above, to the lines 12 to the diaphragms 102 in FIGS. 2E-2H. When pressure is applied above a hole, then one of the diaphragms 102 will operate to cause its associated pilot valve 85 to be driven leftward. This will cause the associated latch valve 14 to be driven leftward also, during the application of pressure to the probe line 81, as the line 34 will be connected to the right-hand side of the central land of the pilot valve 85. Accordingly, the right-hand end of the latch valve 14 will have pressure applied thereto. Referring to latch valve 14-16 on the left-hand side of FIG. 2F, the numeral 1416 indicates that the latch valve is connected to the 16- inch piston adder 140 by means of lines 141 and 142. The right-hand one of the lines 142 is the one which will have the pressure applied to it in a case in which the pilot valve has been actuated by the reader. It will be seen that the line 142 passes through the velocity control valve 17 in FIG. 21, and if pressure is applied on line 94, then the spool valve 143 will be driven to the right and the orifice through the velocity control valve 17 will be reduced for the longer ones of the piston adders from lengths of 16 inches down to 1 inch. As pressure is applied through line 142, the fluid will flow through line 342 into the space in cylinder 145 to the right of piston 144. If the load is released from alignment or if other pistons are also being displaced at the same time, as in the case of exchange between pistons, then there will be freedom for the cylinder 145 to move relative to the piston 144, and, of course, since the pressure is applied to the right-hand side of the piston and cylinder, the cylinder will move to the right. In the opposite case, the piston 144 would move to the left, if the load were released. In FIGS. 3A and 3B, a graph is shown of the displacement characteristic for the 2-inch piston adder 146 and the l-inch piston adder 147. In FIG. 2!, the 1-inch piston adder 147 is shown with its piston 148 extended in cylinder 149, whereas the 2-inch piston adder 146 is shown with the piston 150 in its collapsed position in cylinder 151. If, for example, it were desired to extend the 2-inch piston adder 146 and to collapse the l-inch piston adder 147 during the exchange period, then the orifice provided by the spool valve 143 in the velocity control valve 17 would be retained open and at that time the pressures applied would be on the lefthand end of piston adder 146 and on the left-hand end of the piston adder 147. If at the same time the damper 18 were released, in the sense that the positioning pistons 80 had pressure removed therefrom, then the shaft 152 could move to the right until the damper piston 153 came to rest at the righthand end of its cylinder 154. Thus, during the exchange mode of operation, in this case, since the damper has a maximum displacement of about one-half inch and since the difference between the 2-inch and l-inch piston adders is 1 inch, the entire assembly from the piston adder cylinder 149, to the right, will be moved about one-half inch to the right. At the same time, the piston 150, which is connected by rod 155 to the piston 148, will move about 1% inches to the right. The cylinder 151 will remain in place. In this manner, very rapid displacement between one or more of the piston adders may occur without any motion of the load and with only slight motion of the damper, if desired. This process is referred to herein as exchange. Exchange can occur at high velocity for two reasons: First, the load is disconnected from the piston adders and accordingly there are no problems associated with braking the heavy load when operating in the rapid exchange mode of operation of the adder drive. Secondly, the orifice or the rate of flow of fluid to the adder drive can be regulated. Such regulation is afforded in two ways. The first way in which regulation of How is accomplished is by means of the bypass poppet 37 in conjunction with its hydraulic control circuit described above. The second way in which flow is controlled is by means of a velocity control valve 17. The velocity control valve 17 is controlled through line 94 by means of the hydraulic logic 20. l-leretofore, when the load had been given an instruction to move from one position to another, a rather lengthy period of time expired during which the piston adders exchanged with each other at the maximum velocity permissible with a full load secured to the end of the output shaft 156 of the adder drive. This was most objectionable and required far longer for the total system to operate. However, after considerable experimentation it was discovered in connection with this invention that the use of the exchange concept of higher velocity displacement of the adder drive when in the idling mode of operation would permit far more rapid overall operation of the system in connection with a serial digital drive.

DAMPER Prior piston adder arrangements have incorporated a damper for each and every one of the piston adder units; which in this case shown in FIGS. 21 and 2J and includes 10 piston adders. Thus, in the past, the instant unit would include 10 dampers.

In accordance with this invention only one damper is required. In FIG. 2J, rod 152 is secured by a bar or plate 157 to a shaft 158 secured to a single damper piston 153. Shaft 158 is secured at its opposite end to a bar or plate 159. The plates 157 and 159 cooperate with the shafts 160 extending from a pair of positioning pistons 80 carried inside cylinder 161 in the housing of the damper 18. The bars or plates 157 and 159 are held in alignment by guide rod 600 extending through plate 159. The pistons 80 are employed for final positioning of the damper piston 153 after it has performed its function of smoothly damping the load, with minimal overshoot, as it is nearing the end of its excursion. Pressure on line 75 is to be removed at the beginning of operation of the damper. Thus, the pins 160 will be retracted or since pressure has been removed therefrom, they will permit the damper to be driven in any desired direction. 

1. An arithmetic hydraulic-drive system including an arithmetic hydraulic drive having a hydraulic input and an output member, said hydraulic input of said drive being connected in a hydraulic pressure circuit, sensing means for providing an output signal, said sensing means having a hydraulic-sensing input and an output, said sensing means being responsive to the velocity of flow of hydraulic fluid at said hydraulic-sensing input by changing its output signal and supplying said output signal to said output, said sensing means having said hydraulic-sensing input coupled into said hydraulic pressure circuit, braking means for selectively arresting said output member of said drive, restrictive means having an input and connected in said circuit, said restrictive means including means for varying the resistance to flow of fluid to and from said arithmetic drive through said circuit in response to signals applied to the input thereof, control means coupled to receive said output signal from said sensing means and responsive to a change of the output signal from said sensing means, said control means having a first output connected to means for releasing said braking means cooperating in response to a change of said output signal to release said braking means in response to reception by said control means of an input signal from said sensing means and said control means having a second output coupled for providing a signal to said input of said restrictive means for varying of the resistance of said restrictive means to provide a higher resistance to flow through said circuit concurrently with releasing of said braking means by said first output from said control means.
 2. A system in accordance with claim 1 wherein said sensing means responds to changes of flow velocity relative to predetermined level.
 3. A system in accordance with claim 1 wherein a portion of said sensing means and a portion of said restrictive means comprise a single element.
 4. A system in accordance with claim 1 wherein said system includes a second sensing means having an output and a hydraulic-sensing input, said last-named input being connected in said circuit for sensing flow after adjustment of said restrictive means to provide a higher resistance to flow, said second sensing means output being connected to a second input to said control means for indicating thereto the development of a flow rate level showing termination of a step of operation of the arithmetic drive.
 5. A system in accordance with claim 1 wherein said sensing means and said restrictive means respectively comprise a flow-sensing valve and a bypass valve in series with a restricted passageway connected in parallel with said flow-sensing valve in said hydraulic circuit.
 6. A system in accordance with claim 5 wherein said bypass valve and restricted passageway include in series therewith a second flow-sensing means connected in said hydraulic circuit.
 7. A system in accordance with claim 6 wherein said second flow-sensing means comprises a flow-sensing valve.
 8. A system in accordance with claim 7 wherein said flow-sensing valve and said second flow-sensing means each comprise a flow-responsive unit having a biasing means urging the flow-responsive unit in the opposite direction from the direction of flow, a central orifice for regulation of flow therethrough, and a transverse passageway for connection to said control means for providing control signals thereto as a function of flow velocity.
 9. Apparatus for fluid control comprising: an inlet connected to the inlet of a first flow valve and to the inlet of a bypass valve, a second flow valve having its inlet connected to the outlet of the bypass valve, each of said first and second flow valves including a switching Passageway for isolated connection in a separate fluid circuit operated as a function of the velocity of flow from said inlet to said outlet during the existence of a pressure differential above a minimum level, between each said inlet and the corresponding outlet, wherein said flow valves have outlets connected together.
 10. Apparatus for fluid control of a drive comprising: an arithmetic drive, an inlet connected to the inlet of a first flow valve and to the inlet of a bypass valve, a second flow valve having its inlet connected to the outlet of the bypass valve, each of said first and second flow valves including a switching passageway for isolated connection in a separate fluid circuit operated as a function of the velocity of flow from said inlet to said outlet during the existence of a pressure differential above a minimum level, between each said inlet and the corresponding outlet, wherein said flow valves have outlets connected together, said flow valves having said outlets interconnected in a circuit to the inlet of said arithmetic drive, a control system for generating command signals, said control system having an input and outputs, said output carrying said command signals, braking means for braking said drive selectively in response to a said command signal coupled to said output, said switching passageways in said flow valves being connected to the input of said control system, said bypass valve including an actuator, said actuator being connected to a said output of said control system, at least one of said flow valves operating a switching passageway to opened and closed positions upon substantial change in flow velocity, thereby to actuate said control system to cause said bypass valve to close thereby eliminating said second flow valve from said circuit, and releasing said braking means, said first flow valve being coupled to a separate input to said control system and effective in response to subsequent transition to flow therethrough below a predetermined level, subsequent to generation of a command signal by said control system releasing said braking means thereby commencing operation of said drive, to signal said control system to terminate the cycle of operation of said control system and reset said control system for another cycle of operation thereby resetting said braking means. 